A network overlay may employ software virtualization to create an additional layer of network abstraction on top of a physical network. Such a network overlay may be used to provide virtual private networking (VPN) for hosts in the network.
Specifically, network routers may be configured to operate using a network overlay protocol to facilitate VPN networking. The protocol may be, for example, Locator ID/Separation Protocol (LISP); however, other suitable alternatives may be utilized, such as Virtual Extensible LAN (VXLAN), Enhanced VLAN (EVLAN), or Identifier Locator Addressing (ILA). Here, the routers create and maintain multiple VPN instances comprising forwarding tables for the routing of user plane traffic associated with different VPNs.
Current implementations of these routers involve remote extranet VPNs to be instantiated locally, so that control plane messages received in the context of these VPNs may be processed. However, when routers support one-to-many extranet VPN deployments, the amount of control plane signaling associated with the extranet VPNs grows in proportion to the number of extranets. At scale, the amount of such control plane signaling may become very large or even prohibitive.